g0201_0300.s0284_peeking_iterator.PeekingIterator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation
Show all versions of leetcode-in-java21 Show documentation
Java-based LeetCode algorithm problem solutions, regularly updated
package g0201_0300.s0284_peeking_iterator;
// #Medium #Array #Design #Iterator #2022_07_06_Time_6_ms_(72.91%)_Space_43.3_MB_(14.85%)
import java.util.Iterator;
// Java Iterator interface reference:
// https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
public class PeekingIterator implements Iterator {
private Iterator it;
private Integer current;
public PeekingIterator(Iterator iterator) {
// initialize any member here.
it = iterator;
current = it.next();
}
// Returns the next element in the iteration without advancing the iterator.
public Integer peek() {
if (current == null) {
current = it.next();
}
return current;
}
// hasNext() and next() should behave the same as in the Iterator interface.
// Override them if needed.
@Override
public Integer next() {
Integer temp = current;
current = it.hasNext() ? it.next() : null;
return temp;
}
@Override
public boolean hasNext() {
return current != null;
}
}